xgettext: Scheme: Reorganize tests.
* gettext-tools/tests/xgettext-scheme-format-1: Renamed from
gettext-tools/tests/xgettext-scheme-5.
* gettext-tools/tests/xgettext-scheme-format-2: Renamed from
gettext-tools/tests/xgettext-scheme-6.
* gettext-tools/tests/Makefile.am (TESTS): Update.
